The studies proposed in this application are directed toward establishing the nutrient level(s) of essential amino acid(s) that will prevent tumor growth both in vitro and in vivo of four murine tumor models. These include the A26 glioma, Lewis lung carcinoma, MCA 2182 fibrosarcoma and B16 melanoma. By varying the level of each of the nine essential amino acids in the nutrient media, we expect to be able to identify those essential amino acids that are critical for the growth of each model system in vitro. Based upon these findings, we will establish the dietary level of those essential amino acids in vivo that will prevent tumor growth without compromising the host and produce prolonged survival. Moreover, we will determine the effects of nutrient restriction of essential amino acids on their transport and other metabolic parameters in vitro and in vivo. In addition, we will ascertain whether dietary essential amino acid restriction will prevent metastasis. Finally, we will establish whether the dietary essential amino acid restriction will have the same effects on each of several cloned lines of a single methylcholanthrene fibrosarcoma in order to determine whether or not tumor heterogeneity is expressed at the level of amino acid requirements.